Evidential Considerations PDF

OFFICIAL Unit 3 Lesson 1...

OFFICIAL Unit 3 Lesson 1 Evidential Considerations Lesson Aim: The learner will be able to explain evidential considerations within crime scenes Learning Outcomes: On successful completion of the lesson, Introduction students will be able to:- Dr Edmond Locard a Forensic Science pioneer formulated the theory that "Every contact leaves a trace". This became known 1. Explain the various types of potential as Locard’s exchange principle. Trace evidence available at crime scenes and evidence can be used to link people or how to preserve them objects to places, other people or other objects and often serves as a starting point or lead for a particular line of investigation. 2. Explain how contamination can impact Trace evidence helps put together pieces of upon a crime scene the criminal investigation puzzle. The careful examination of the scene of a 3. State the phases of your initial actions at crime by trained and experienced police and crime scenes civilian Scenes of Crime Officers and forensic scientists is a vitally important part of criminal investigation. 4. State the entries you should make in In the management of most crime scenes, a your notebook and Scene Entry Log at a number of stages can be identified:- crime scene The discovery of a crime scene 5. Provide examples of Health and Safety The protection and preservation of the considerations at crime scenes crime scene The sequential examination of the crime scene. You will often be the first officer to arrive at an incident and every one you attend is potentially the scene of a crime. Each scene that you attend will be different and should be treated as such. 1 th Amended 24 April 2024 v.5 OFFICIAL  OFFICIAL Unit 3 Lesson 1 Evidential Considerations Contact Evidence There are many types of contact evidence and the most common types are:- Fingerprints Most fingerprints are made from an individual’s sweat deposits. Fingerprints can be found in a variety of media such as saliva, blood, oil or grease and can be retrieved from different surfaces including glass, metal, wood, plastics, ceramics and paper. Preservation Consider the scene of a housebreaking with a quantity of broken glass lying on the ground outside the premises near to a point of entry. If the glass is protected from the weather and from being handled, it could be left in situ. If not, it should be moved and placed somewhere safe and dry. Pick up glass by the edges and try to avoid accidentally erasing fingerprints. If you do find it necessary to protect an item in some way or have to move an article, note this carefully and tell the Scene Examiner and if deployed a Crime Scene Manager. DNA Deoxyribo-Nucleic Acid is the name of the chemical which is found in virtually every cell in the body and which carries genetic information from one generation to the next. Except for identical twins, each person’s DNA is unique and can be retrieved from virtually any surface or item including cups, cigarette ends, partially eaten foods or discarded clothing. Preservation At scenes where DNA evidence may have been left, items should be kept away from any likely contamination sources. Your own DNA can contaminate items. When moving items you should always use gloves to protect both yourself and the crime scene. Saliva transfer caused by coughing or talking over an unprotected item can also cause contamination. 2 Scots Criminal Law: Police Powers and Principles of Evidence PoOFFICIAL  OFFICIAL Unit 3 Lesson 1 Evidential Considerations Shoe Impressions Footwear marks can be successfully recovered from a variety of surfaces, hard or soft. Every footstep could potentially leave an impression and footwear marks could be at crime scenes, although initially they may not be obvious. Preservation If a shoe impression is evident, try to preserve it. A box or similar can be used to cover them if they are outside. If footwear impressions appear inside the premises on windowsills, kitchen work surfaces or furniture, ask the occupier not to clean them prior to the crime scene being examined. Hairs and Fibres Hairs and fibres are the most common materials transferred during physical contact between two or more people. Hairs and fibres are most commonly examined to prove contact between two individuals in rape, murder and assault cases. Preservation If you need to take possession of clothing from a victim, witness or suspect to preserve the potential fibre evidence, you must seize it as soon as possible. Fibres and hairs fall very rapidly from clothing and once they are gone there is no chance of getting them back. Each item should be placed in a separate bag to preserve fibres or hair. If a vehicle is to be examined, do not sit in it. Fibres and contact traces from your clothing will be transferred to the seats and you may remove evidence from the vehicle onto your clothing. Marks Marks occur when two surfaces come into firm contact with each other. Some marks are recognised as evidence types in their own right, such as footwear and fingerprints. However forensic techniques can enable almost any mark to be linked to the item that made it. Tools possess unique characteristics consisting of manufacturing irregularities and damage caused by use. When the tool is forced against a surface it records an image of this detail. If microscopically examined, sufficient detail can conclusively link items together. 3 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 1 Evidential Considerations Preservation If you are at a scene of a crime and you see that there are instrument marks, do not put anything into the mark. Even if there is a tool recovered from a suspect do not attempt to fit the tool back into the mark as this may destroy evidence. Cover the mark if there are adverse weather conditions. Paint and Glass Paint, glass and many other types of debris are used to link suspects to crime scenes. The strength of this evidence will depend on the material concerned and the circumstances of the case. Paint is usually transferred in the form of minute flakes or smears onto clothing, vehicles or tools. Paint evidence is normally associated with housebreakings and vandalisms where paint from damaged doors and windows has transferred onto clothing and tools. It is also associated with road traffic accidents where paint can transfer to a victim or between vehicles. Preservation Paint flakes and glass fragments are lost very rapidly from hair and clothing, as are most other types of debris. It is therefore crucial to recover clothing and footwear from a suspect when required as soon as possible. Cross Contamination Contact evidence at crime scenes can have a very high evidential value. It is therefore essential that all steps possible be taken to prevent the evidence not only being damaged or lost but also ‘contaminated’. This contamination is interference, often caused unwittingly by humans, animals or other means. If visiting a crime scene or victim, you should avoid dealing with any suspect for that offence. Also, consideration should be given to attending additional crime scenes. Victims and suspects should not be transported in the same vehicles. If contamination is found to have occurred the findings of any scientific examination may be rendered valueless. 4 Scots Criminal Law: Police Powers and Principles of Evidence PoOFFICIAL  OFFICIAL Unit 3 Lesson 1 Evidential Considerations Always make the scene examiner and/or Crime Scene Manager aware of any possible occurrence of contamination or any concerns that you have. Activity 1 A1 You attend at Sylvester's Nite Club, Brookbank where a male has been assaulted and stabbed in the street outside. Assuming the victim has been taken into hospital, what kind of forensic evidence might be found at the scene. Please list:- Initial Action at a Crime Scene The initial actions you take at a crime scene can be vitally important. APC is an easy way to remember the three fundamental steps for managing any crime scene. Assess Protect Communicate 5 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 1 Evidential Considerations Feedback 1 F1 There may well be blood samples, hair, fibre, broken glass, a blood stained knife, footprints and bloody clothing. The list is substantial. THIS IS WHY YOU MUST PRESERVE THE SCENE. Assess On your arrival try to identify the exact crime scene, i.e. where it is, what it is and how big it is. Assess the situation as quickly and as carefully as you can. This will help you decide on the most appropriate action. The first duty of a police officer at a scene is to preserve life. Preservation of life will always be the first priority. If a victim is still alive you should:- Render aid and assist other better-qualified personnel to do so Observe exact details of scene and location of victim Ensure removal of any victim with minimum disturbance Manage the routes in/out known as the Common Approach Path Record all facts and report them to your supervisors or SIO Normal hospital procedures thereafter. You should assume however, that the offender has left contact evidence at the scene, so take great care to minimise any disruption to a scene. Look where you step and try to avoid the obvious route(s) which the offender may have taken to get to and leave the scene. Advise other personnel to use the same route as you and use the same route to and back from the victim. This is called the Common Approach Path (CAP). Police Cordon Tape can be used to define the Common Approach Path. 6 Scots Criminal Law: Police Powers and Principles of Evidence PoOFFICIAL  OFFICIAL Unit 3 Lesson 1 Evidential Considerations Protect The second duty is to protect the scene against people and the elements. If this is not carried out effectively there will be unnecessary loss of evidence. To protect the scene it should be cordoned off as soon as practicable. The cordon can be put in place with tape showing unauthorised personnel and the public that they must not enter the area. If the scene is indoors the cordon should include the crime scene and where possible the probable entry and exit paths used by the criminal. Any cordon you do put up should include not just the focal point of the crime scene but the area around it too. It is better to have a large area cordoned off than one that is too small. A decision to reduce a cordon size can always be made by others later. Communicate Communication is the key to effective investigation and professional crime management. Throughout your initial assessment and protection of any crime scene you will be engaged in communication, asking questions, establishing facts and giving advice and assistance if necessary. You must report the full situation at the scene to your control room. Your communication will ensure that you receive the proper assistance for the investigation from relevant personnel. Notebook Entry If you are the first officer attending, it is important that you note relevant details in your notebook/mobile device such as:- Time called to scene and arrival time Persons present on your arrival Weather conditions Exact position of key pieces of evidence, e.g. a body, a weapon, etc. Exact position of objects in and around the scene Signs of a struggle Location of keys 7 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 1 Evidential Considerations Were doors and windows open or closed, locked or broken Foot impressions Marks left by a vehicle Rough sketch of crime scene etc. Odours (e.g. cigarette smoke, perfume or aftershave) Lights on or off Details of other people involved at this stage, such as doctors or paramedics should be noted. This will enable any fingerprints, footprints or DNA they have left to be eliminated Time of arrival or departure of personnel at a scene As an initial responder to a serious incident, you may need to decide whether to start a Scene Entry Log once a cordon is in place. If in doubt, seek guidance from your Supervisor. Scene Entry Log You may be designated as a ‘Loggist’ at the scene of a crime/incident and be required to complete a Scene Entry Log (Appendix A)whilst guarding a location and restricting access to the scene. This Log should be available to you as part of the police equipment kept in police vehicles. The information required in the Log will include:- Details of the officer keeping the log Reason for entering crime scene Movements/actions at crime scene Arrival and departure time (including the Loggists!) Names of personnel attending at scene DR MAN is an easy way to remember the information that should be logged when guarding a crime scene location. It is important to recognise that the Scene Entry Log may become a production in a future case and as such, may be subject to scrutiny during trial. Where the Scene Entry Log is not accurately completed, this could bring the integrity of a locus protection into question and lead to a trial collapsing. As such Loggists MUST be meticulous when performing their role and ensure the Log is completed accurately and in full. 8 Scots Criminal Law: Police Powers and Principles of Evidence PoOFFICIAL  OFFICIAL Unit 3 Lesson 1 Evidential Considerations Health and Safety HS When entering a Crime Scene be aware of health and safety concerns pertaining to yourself, your colleagues, partner agencies and the public. Crime scenes can be complex and can present safety risks to personnel, depending on the incident you are attending. Even when all reasonably practicable controls have been taken there will often be a residual risk that may well be substantial. Circumstances where there are foreseeable risks include:- Electrical, Structural and Fire risks within buildings particularly Cannabis cultivations being identified Incidents involving Chemical, Gas or Bio Hazards Body fluids, drugs and offensive weapons when searching persons or property Dealing with violent individuals Controlling large crowds, such as planned/unplanned protests, sporting events etc. Attending incidents related to natural hazards such as open water Operational activities during periods of severe weather This list is not exhaustive but gives examples of the varied types of incidents where health and safety concerns must be considered. 9 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 1 Evidential Considerations Appendix A 10 Scots Criminal Law: Police Powers and Principles of Evidence PoOFFICIAL  OFFICIAL Unit 3 Lesson 1 Evidential Considerations For further information, use the resources shown below:- There is no further reading for this lesson Review: You can explain the various types of potential evidence available at crime scenes and how to preserve them You can explain how contamination can impact upon a crime scene You can state the three phases of your initial actions at crime scenes You can state the entries you should make in your notebook and Scene Entry Log at a crime scene You can provide examples of Health and Safety considerations at crime scenes 11 Scots Criminal Law: Police Powers and Principles of Evidence OFFICIAL  OFFICIAL Unit 3 Lesson 1 Evidential Considerations Learning Log: How will what you have learned in this module impact your day-to- day role? Are there any skills or knowledge you would like to develop further following this module? End of Module 12 Scots Criminal Law: Police Powers and Principles of Evidence PoOFFICIAL